For example, a multilayer ceramic capacitor is produced by the procedure below.
First, dielectric slurry obtained by dispersing inorganic colorant powder (ceramic dielectric powder) in a solvent including a nonvolatile organic component, such as a dispersant, polymeric resin and plasticizer, is produced. Next, the dielectric slurry is applied to a plastic support film by the doctor blade method, nozzle method or other means and dried to obtain a dielectric green sheet.
Next, an electrode pattern layer is formed on the dielectric green sheet. The electrode pattern layer is generally formed by performing screen printing of an electrode paste.
Next, the dielectric green sheet including the electrode pattern layers is removed from the support base film, cut to be a predetermined size, then, stacked for a plurality of times while aligning pattern positions of the electrode pattern layers, pressured and bonded, so that a ceramic green multilayer body is obtained. Next, the multilayer body is cut to be a predetermined size to form a chip, then, fired at a predetermined temperature and atmosphere. The thus obtained fired body chip is applied with external electrodes and burnt at its end portions, so that a multilayer ceramic capacitor is completed.
In the production procedure of the multilayer ceramic capacitor as above, when forming an electrode pattern layer in a predetermined pattern on the dielectric green sheet, there is a level difference gap blank portion, on which the electrode pattern layer dose not exist. Due to the level difference gap portion, a level difference is formed on a surface of the dielectric green sheet. A number of the electrode pattern layers with the level difference gap portion are stacked via green sheets. Since the stacked body is pressured and bonded after that, the level difference gap portions are crushed. Therefore, the larger the number of stacked layers of the multilayer body and the thinner a thickness of the green sheet is, the larger the effects of the accumulated level difference becomes.
As a result, a green sheet sandwiched by the portions of the electrode pattern layers is tightly pressured and bonded to obtain a high density, while a density of a green sheet sandwiched by portions having the level difference gap portions becomes lower comparing with that on other portions, so that a density difference arises in the multilayer ceramic body. Also, there arises a disadvantage that adhesiveness with the upper and lower green sheets declines in the green sheet sandwiched by the portions with the level difference gap portions.
The multilayer body is cut to be a chip after that, then, fired, but when a multilayer body having the above problem is fired, it easily cracks between layers, which has to be overcame. Also, there is a problem that structural defects, such as chip deformation, a short-circuiting defect, cracks and delamination, often arise after firing the multilayer body.
To solve the above problems, for example as shown in the patent articles 1 to 5 below, methods of burying a level difference gap portion with a blank pattern layer generated by printing an electrode paste have been proposed. According to these methods, a surface including an electrode layer can be made flat and the problems in the ceramic capacitor due to a level difference as explained above can be improved.
Patent Article 1: The Japanese Unexamined Patent Publication No. 56-94719
Patent Article 2: The Japanese Unexamined Patent Publication No. 3-74820
Patent Article 3: The Japanese Unexamined Patent Publication No. 9-106925
Patent Article 4: The Japanese Unexamined Patent Publication No. 2001-126951
Patent Article 5: The Japanese Unexamined Patent Publication No. 2001-358036